Thanks, I’ll try that ! 
I have to agree with that. Whilst using the volume knob is a potentially useful tool, trying to get the level right when switching from rhythm to lead and back is a bit tricky.
Presetting a level on a foot switch is a lot easier to manage IME
A lot of the Boss stuff has a solo boost setting for the preamps and for some of the boost/overdrive pedals which can switch the level up for solos using a foot switch. I’ve found myself using that quite a lot recently.
Cheers,
Keith